wrlib/gif.c

   1 /* gif.c - load GIF image from file
   2  *
   3  * Raster graphics library
   4  *
   5  * Copyright (c) 1998-2003 Alfredo K. Kojima
   6  *
   7  *  This library is free software; you can redistribute it and/or
   8  *  modify it under the terms of the GNU Library General Public
   9  *  License as published by the Free Software Foundation; either
  10  *  version 2 of the License, or (at your option) any later version.
  11  *
  12  *  This library is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  *  Library General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU Library General Public
  18  *  License along with this library; if not, write to the Free
  19  *  Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
  20  *  MA 02110-1301, USA.
  21  */
  22
  23 #include <config.h>
  24
  25 #ifdef USE_GIF
  26
  27 #include <stdlib.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30
  31 #include <gif_lib.h>
  32
  33 #include "wraster.h"
  34 #include "imgformat.h"
  35
  36 static int InterlacedOffset[] = { 0, 4, 2, 1 };
  37 static int InterlacedJumps[] = { 8, 8, 4, 2 };
  38
  39 /*
  40  * Partially based on code in gif2rgb from giflib, by Gershon Elber.
  41  */
  42 RImage *RLoadGIF(const char *file, int index)
  43 {
  44         RImage *image = NULL;
  45         unsigned char *cptr;
  46         GifFileType *gif = NULL;
  47         GifPixelType *buffer = NULL;
  48         int i, j, k;
  49         int width, height;
  50         GifRecordType recType;
  51         ColorMapObject *colormap;
  52         unsigned char rmap[256], gmap[256], bmap[256];
  53
  54         if (index < 0)
  55                 index = 0;
  56
  57         /* default error message */
  58         RErrorCode = RERR_BADINDEX;
  59
  60         gif = DGifOpenFileName(file);
  61
  62         if (!gif) {
  63                 switch (GifLastError()) {
  64                 case D_GIF_ERR_OPEN_FAILED:
  65                         RErrorCode = RERR_OPEN;
  66                         break;
  67                 case D_GIF_ERR_READ_FAILED:
  68                         RErrorCode = RERR_READ;
  69                         break;
  70                 default:
  71                         RErrorCode = RERR_BADIMAGEFILE;
  72                         break;
  73                 }
  74                 return NULL;
  75         }
  76
  77         if (gif->SWidth < 1 || gif->SHeight < 1) {
  78                 DGifCloseFile(gif);
  79                 RErrorCode = RERR_BADIMAGEFILE;
  80                 return NULL;
  81         }
  82
  83         colormap = gif->SColorMap;
  84         i = 0;
  85
  86         do {
  87                 int extCode;
  88                 GifByteType *extension;
  89
  90                 if (DGifGetRecordType(gif, &recType) == GIF_ERROR)
  91                         goto giferr;
  92
  93                 switch (recType) {
  94                 case IMAGE_DESC_RECORD_TYPE:
  95                         if (i++ != index)
  96                                 break;
  97
  98                         if (DGifGetImageDesc(gif) == GIF_ERROR)
  99                                 goto giferr;
 100
 101                         width = gif->Image.Width;
 102                         height = gif->Image.Height;
 103
 104                         if (gif->Image.ColorMap)
 105                                 colormap = gif->Image.ColorMap;
 106
 107                         /* the gif specs talk about a default colormap, but it
 108                          * doesnt say what the heck is this default colormap
 109                          * Render anything */
 110                         if (colormap) {
 111                                 for (j = 0; j < colormap->ColorCount; j++) {
 112                                         rmap[j] = colormap->Colors[j].Red;
 113                                         gmap[j] = colormap->Colors[j].Green;
 114                                         bmap[j] = colormap->Colors[j].Blue;
 115                                 }
 116                         }
 117
 118                         buffer = malloc(width * sizeof(GifColorType));
 119                         if (!buffer) {
 120                                 RErrorCode = RERR_NOMEMORY;
 121                                 goto bye;
 122                         }
 123
 124                         image = RCreateImage(width, height, False);
 125                         if (!image)
 126                                 goto bye;
 127
 128                         if (gif->Image.Interlace) {
 129                                 int l, pelsPerLine;
 130
 131                                 if (RRGBAFormat == image->format)
 132                                         pelsPerLine = width * 4;
 133                                 else
 134                                         pelsPerLine = width * 3;
 135
 136                                 for (j = 0; j < 4; j++) {
 137                                         for (k = InterlacedOffset[j]; k < height; k += InterlacedJumps[j]) {
 138                                                 if (DGifGetLine(gif, buffer, width) == GIF_ERROR)
 139                                                         goto giferr;
 140
 141                                                 cptr = image->data + (k * pelsPerLine);
 142                                                 for (l = 0; l < width; l++) {
 143                                                         int pixel = buffer[l];
 144                                                         *cptr++ = rmap[pixel];
 145                                                         *cptr++ = gmap[pixel];
 146                                                         *cptr++ = bmap[pixel];
 147                                                 }
 148                                         }
 149                                 }
 150                         } else {
 151                                 cptr = image->data;
 152                                 for (j = 0; j < height; j++) {
 153                                         if (DGifGetLine(gif, buffer, width) == GIF_ERROR)
 154                                                 goto giferr;
 155
 156                                         for (k = 0; k < width; k++) {
 157                                                 int pixel = buffer[k];
 158                                                 *cptr++ = rmap[pixel];
 159                                                 *cptr++ = gmap[pixel];
 160                                                 *cptr++ = bmap[pixel];
 161                                                 if (RRGBAFormat == image->format)
 162                                                         cptr++;
 163                                         }
 164                                 }
 165                         }
 166                         break;
 167
 168                 case EXTENSION_RECORD_TYPE:
 169                         /* skip all extension blocks */
 170                         if (DGifGetExtension(gif, &extCode, &extension) == GIF_ERROR)
 171                                 goto giferr;
 172
 173                         while (extension)
 174                                 if (DGifGetExtensionNext(gif, &extension) == GIF_ERROR)
 175                                         goto giferr;
 176
 177                         break;
 178
 179                 default:
 180                         break;
 181                 }
 182         } while (recType != TERMINATE_RECORD_TYPE && i <= index);
 183
 184         /* yuck! */
 185         goto did_not_get_any_errors;
 186  giferr:
 187         switch (GifLastError()) {
 188         case D_GIF_ERR_OPEN_FAILED:
 189                 RErrorCode = RERR_OPEN;
 190                 break;
 191         case D_GIF_ERR_READ_FAILED:
 192                 RErrorCode = RERR_READ;
 193                 break;
 194         default:
 195                 RErrorCode = RERR_BADIMAGEFILE;
 196                 break;
 197         }
 198  bye:
 199         if (image)
 200                 RReleaseImage(image);
 201         image = NULL;
 202  did_not_get_any_errors:
 203
 204         if (buffer)
 205                 free(buffer);
 206
 207         if (gif)
 208                 DGifCloseFile(gif);
 209
 210         return image;
 211 }
 212
 213 #endif                          /* USE_GIF */